Adjustable seat mounting mechanism

ABSTRACT

A seat mounting mechanism for mounting a seat for adjustable fore and aft movement, the mechanism having an elongate fixed rail which is adapted to be securable to a substructure, pan or floor, a movable rail which is engageable with the fixed rail and adapted to be securable to a seat, and at least one locking member mounted on a first one of the fixed rail and the movable rails. The locking member is pivotable between an engagement position in which it locks the movable rail relative to the fixed rail and a retracted position in which it frees the movable rail for adjustment along the fixed rail. The locking member is mounted on the first rail for pivotable movement, between the engagement and retracted positions, about a pivot axis extending substantially parallel to the rails. The locking member has an engagement mechanism by which it is selectively engageable with an engagement mechanism of, and disposed along, a second one of the rails when the locking member is in its engagement position. The engagement mechanism of the locking member is laterally engageable with the engagement mechanism of the second rail.

This application is the national phase under 35 U.S.C. §371 of prior PCTInternational Application No. PCT/AU 96/00410 which has an Internationalfiling date of Jul. 2, 1996 which designated the United States ofAmerica, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved adjustable mechanism formounting a seat for fore and aft movement. The invention has particularapplication in the mounting of motor vehicle seats although, whilegenerally described in relation to that application, it is to beunderstood that the mechanism also can be used for mounting other typesof seats.

2. Description of Related Art

An existing and well known type of adjustable, vehicle seat mountingmechanism has a fixed rail and a movable rail which is engaged with thefixed rail for movement therealong. The mechanism also includes alocking member which is mounted on one of the rails and which ispivotable between an engagement position in which it locks the movablerail relative to the fixed rail by projecting, usually laterally,through at least one pair of aligned apertures of the two rails, and aretracted position in which it frees the movable rail for adjustmentalong the fixed rail. As installed in a vehicle, the fixed rail of eachof two laterally spaced mechanisms is secured to the substructure, panor floor of the vehicle, with each movable rail secured to the undersideof a seat of the vehicle. The locking members of the two mechanisms areinter-connected so as to be pivotable in unison, such as under theaction of a release bar associated with one of the mechanisms.

While there are many forms of vehicle seat mounting mechanisms of thatgeneral type, examples are shown by U.S. Pat. Nos. 4,168,051 to Terada,4,629,254 to Stolper et al and 4,958,799 to Clauw et al. Each of thesepatents illustrate a usual characteristic of known forms of mechanisms;namely, that they are formed from a metal plate, typically of steel, byroll forming, pressing and/or stamping. A further usual characteristicis that the rails are inter-engaged by a channel form of one receiving achannel form of the other. Often the channel form of the movable rail issimply slidable in or on the fixed rail, although U.S. Pat. No.4,958,799 (Clauw et al) shows an arrangement in which bearing means areprovided between the rails. A departure from the usual characteristic ofrails formed from a metal plate is shown by International patentspecification WO95/02520 (Clausen/Norsk Hydro A.S.). in which the railsare extruded, such as from an aluminium alloy.

There are design constraints on mechanisms having componentsconventionally formed from a metal plate. There is also difficulty inachieving a suitable balance between weight and strength. Vehiclemanufacturers seek to minimise the weight of all vehicle components.However, the sectional thicknesses of the metal plate for the mechanismscan only be reduced to a certain limit. Therefore, there is a limit towhich the weight can be reduced if strength is not to be compromised. Ofcourse, a countervailing pressure for vehicle manufacturers is safety,and strength can not be adversely compromised if safety standards are tobe satisfied. The proposal of WO95/02520 offers the possibility ofweight saving, by utilising the more favorable weight to strength ratioof aluminium alloys. However, while extrusion of rails of an aluminiumalloy obviates some of the design limitations inherent in processes forforming mechanisms from a metal plate, it introduces other limitations.

SUMMARY OF THE INVENTION

The present invention is directed to providing an improved adjustableseat mounting mechanism which enables use of materials of constructionproviding a more favorable weight to strength ratio. These include lightmetals, such as alloys of aluminium, zinc and magnesium, of whichmagnesium alloys are particularly preferred. However, the invention alsoenables use of suitable metal matrix composite materials, metalcomponents made by powder metallurgy processes and engineering plasticsmaterials.

The mechanism of the present invention has an elongate fixed rail whichis adapted to be secured to a substructure, pan or floor of a vehicle(or to another substructure in the case of a non-vehicular application),an elongate movable rail which is engaged with the fixed rail and isadapted to be secured to the underside of a seat, and at least onelocking member mounted on one of the rails and pivotable between anengagement position in which it locks the movable rail relative to thefixed rail and a retracted position in which it frees the movable railfor adjustment along the fixed rail.

The mechanism of the invention is intended to be used so as to provide amounting for a seat along one side of the latter, to enable adjustmentof the position of the seat in the direction of the rails. A similarmechanism is used to provide a mounting for the seat along its otherside with the rails of each mechanism substantially parallel. Anactuator may provide for common pivoting of the locking member of eachmechanism to its retracted position. Alternatively, the actuator may actto pivot the locking member of one mechanism, with this pivoting causingsimultaneous pivoting of the locking member of the other mechanism.

The fixed and movable rails of the mechanism of the present inventionmay be cast from a suitable light metal. The casting process may begravity casting, pressure casting such as pressure diecasting, orsqueeze casting or squeeze forming. Alternatively, the rails may be madeof an engineering plastics material by a suitable molding process, suchas injection moulding. With use of either metal or plastics material,casting or molding provides substantial freedom of design in the form ofthe rails, the arrangement by which the movable rail can be adapted forengagement with the fixed rails, and in the form of the locking memberand its engagement with the rails.

The fixed rail may be of unitary construction. Alternatively, it may beof multi-part construction, comprising separately formed elongatecomponents which are secured together. In the latter case, thecomponents may interfit longitudinally, such as by frictional engagementtherebetween, for example by means of a longitudinal tongue of onecomponent being received within a groove defined by the other component.Securement of the components may be by means of bonding therebetween,such as where they interfit, by retention clips, by screw-threadedfasteners or, when appropriate for the material of construction, bywelding. However, the movable rail preferably is of unitaryconstruction.

The fixed rail may define an upwardly facing, longitudinal bearingsurface on which the movable rail is supported. The movable rail maydefine a downwardly facing, longitudinal bearing surface by which it issupported on the fixed rail for movement therealong. The fixed andmovable rails may be in direct, sliding contact at the respectivebearing surfaces where they are formed of a plastics material having lowfriction characteristics, or where a lubricant is provided between thebearing surfaces. Alternatively, the fixed and movable rails may be inindirect contact at the respective bearing surfaces, by provision ofbearing means, such as roller bearings, slippers or the liketherebetween. However, in a highly preferred form of the invention, themovable rail is an upper rail which is supported on the lower rail, incontrast to the usual prior art arrangement in which the rails arelaterally adjacent.

In one particularly suitable arrangement, each rail has two longitudinalbearing surfaces which are mutually inclined to enhance self-alignmentduring longitudinal movement of the movable rail on the fixed rail. Inone form of that arrangement, the fixed rail has an upwardly facing,longitudinal surface which has the form of a V-section trough, each sideof which defines one of two mutually inclined bearing surfaces, with themovable rail having a downwardly facing, longitudinal surface ofcomplementary form, defining two mutually inclined bearing surfaces. Inanother form of the arrangement, the surfaces are of a converse form, inthat the downwardly facing surface of the movable rail has the form of aV-section trough. With each form, a respective roller means or slippermay be provided between each of opposed pairs of bearing surfaces.

At least where the rails have such a self-aligning arrangement, they maybe held in engagement by engagement between their bearing surfaces andby the locking member. Thus, the locking member may be a principal meanspreventing the movable rail from lifting from the fixed rail. However,there may be other means to prevent such lifting. In preferred forms,the mechanism of the present invention has further engagement betweenthe rails which constrains the movable rail from lifting from the fixedrail. In one convenient arrangement, the fixed rail has a side wallalong at least one side of the movable rail, and a laterally extending,longitudinal rib on either the side wall or the movable rail is locatedin a laterally open, longitudinally extending slot in the other one ofthe movable rail and the side wall. In general, it is preferred that therib is on the side wall of the fixed rail, with the groove defined bythe movable rail. However, the converse is possible.

The locking member may be made of a suitable metal, and it may be castof the same or a different material to that used for the rails.Alternatively, the locking member may be made of an engineering plasticsmaterial. The method of forming may be as described in relation to therails. That is the locking member may be die cast, produced by squeezecasting or forming, cast in sand molds or by investment casting, or itmay be injection molded, depending on the material of which it isformed.

The locking member may be of unitary construction. Alternatively, it maybe formed from two or more separately formed components which aresecured together. In the latter case, securement can be as describedwith reference to the fixed rail. However, where of more than twocomponents, the locking member is amenable to this necessitating onlytwo component forms, distinguished for ease of reference as an end partand an intermediate part. In the latter case, the locking member maycomprise two end parts which are assembled together, either directly orwith at least one intermediate part therebetween.

The locking member is pivotably mounted on either the fixed rail or themovable rail, so as to be reversibly pivotable, preferably about alongitudinal axis substantially parallel to the rails. In either case,the locking member is adapted for pivotal movement on that one railbetween its engagement and retracted positions. The locking memberpreferably is biased to the engagement position by a resilient biasingmeans, such as a helical, torsion or leaf spring, and pivotable to itsretracted position against the action of the biasing means.

The locking member is adapted for locking engagement, when in itsengagement position, with the other one of the rails; that is, with therail on which it is not pivotably mounted. This engagement with theother rail is possible with the movable rail in any of a plurality ofpositions to which that rail is movable along the fixed rail. Theengagement is by either of two converse arrangements. In the first ofthese, each of selected lateral projections of a plurality oflongitudinally spaced projections of the other rail, is receivable inrespective laterally open grooves, recesses or the like of the lockingmember. In the second of those arrangements, the laterally open grooves,recesses or the like are provided on the other rail and each receives arespective lateral projection of the locking member.

In some known mechanisms, engagement generally is by each of laterallyprojecting fingers of a locking member engaging in aligned apertures ofeach rail. This form of simultaneous engagement with each rail is notnecessary in the mechanism of the present invention. However, it isdesirable in the mechanism of the present invention that the lockingmember be separately engageable with each rail by means of lateralprojections received in laterally open grooves, recesses or the like, asthis is found to enhance the locking action of the locking member. Wherethe locking member is so simultaneously engageable, this can be in anintegrated form in that the locking member may have grooves, recesses orthe like with each of these receiving a respective projection of eachrail, or the locking member may have projections each receivable in agroove, recess or the like of each rail. Alternatively, the lockingmember may have projections receivable in grooves, recesses or the likeof one rail, and also have grooves, recesses or the like in which arereceivable projections of the other rail.

The locking member may extend from its pivot axis across one side of therails, then laterally with respect to the rails and have an end portionthereof which extends across to the other side of at least one of therails. Where this is the case, the locking member may, for example, beat least partly of arcuate form transversely of its pivot axis and therails. The arrangement may be such that the locking member is biased toits engagement position to achieve engagement with the other rail, thatis the rail on which it is not pivotably mounted, at the one side of therails. Where so biased, the end portion may define an abutment surfacewhich engages at least one of the rails, at the other side, so as tolimit pivoting of the locking member from its engagement position andthereby determine the retracted position.

For the purpose of describing arrangements in which the locking membercan be pivotably mounted, it is convenient to do so in the context ofthe movable rail being an upper rail supported on the fixed rail, withthe locking member disposed to one side of each rail. In a firstarrangement applicable to that context, the locking member is mounted atan upper extent thereof on the movable rail, so as to be pivotable on anaxis parallel with that rail. The locking member depends from the pivotaxis, below a region along which the movable rail is supported on thefixed rail to a region at which the locking member when in itsengagement position is selectively engaged with the fixed rail. When inthat position, the locking member engages the fixed rail so as toprevent movement of the movable rail therealong. The arrangementpreferably is such that the locking member is pivotable towards and awayfrom the fixed rail in movement respectively to its engagement andretracted positions, with its engagement with the fixed rail separatefrom its mounting on, or other engagement with, the movable rail.

A second arrangement applicable to the above context is the converse ofthe first arrangement. That is, the locking member is mounted at a lowerextent thereof on the fixed rail, and extends upwardly from a pivot axisparallel to that rail, above a region along which the movable rail issupported on the fixed rail, to a region at which the locking memberwhen in its engagement position is selectively engaged with the movablerail.

In a highly desirable form of the first and second arrangements, thelocking member not only is able to lock the rails, but also acts to holdthe movable rail down onto the fixed rail. In the first arrangement,this can be by an upwardly facing surface defined by the locking memberbeing able to bear against a downwardly facing surface of the fixed railwhen the locking member is in its engagement position. In the secondarrangement, a downwardly facing surface defined by the locking membercan bear against an upwardly facing surface of the movable rail.

In the first and second arrangements, the locking member can bepivotably mounted so as to laterally engage the fixed or movable rail,respectively, by pivoting towards the same side of each rail. For this,the locking member may be pivotably mounted on the same side of themovable or fixed rail as the side of the fixed or movable rail,respectively, it is to engage. However, other mounting arrangements arepossible. Thus, the locking member may have at least one arm whichprojects through an opening of the rail on which the locking member ispivotably mounted. With the mounting being at a side of that rail whichis opposite to the side of the other rail with which the locking memberis to be selectively engageable. Preferably the locking member has atleast two such arms, each of which projects through a respective openingof the rail on which the locking member is mounted.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be understood in further detail,description now is directed to the accompanying drawings, in which:

FIG. 1 is a partial transverse section through a first form ofadjustable seat mounting mechanism according to the present invention;

FIG. 2 is an exploded, perspective view of a modified form of acomponent of FIG. 1;

FIG. 3 is an exploded, perspective view of components similar to thoseof FIG. 1, but incorporating the modification of FIG. 2;

FIG. 4 corresponds to FIG. 1 but shows a second form of the mechanismaccording to the present invention;

FIG. 5 is a partial side elevation of a component of the mechanism ofFIG. 4; and

FIG. 6 is a perspective view of a further component of the mechanism ofFIG. 4;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 to 3, the mechanism 10 shown therein has anelongate lower rail 12, an elongate upper rail 14 and a locking member16. The rail 12 supports the rail 14 thereon. Locking member 16 ispivotably mounted on upper rail 14 and is reversibly pivotable on anaxis parallel to rails 12, 14, as shown by arrow X, between anengagement position shown in FIG. 1 and a retracted position (shown inbroken outline) which is anticlockwise with respect to its position inFIG. 1. Locking member 16 locks rail 14 against movement longitudinallyof rail 12 when in its engagement position, but frees rail 14 for suchmovement when in its retracted position Locking member 16 is movable toits engagement position by suitable means (not shown) for example,resilient biasing means such as a spring.

In FIG. 1, the lower rail 12 is shown as being of integral form However,as shown by the modification of FIG. 2, the rail 12 can comprise twoelongate parts 13 and 15 which are formed separately for ease ofmanufacture, and which are able to be secured in assembly. The parts 13and 15 of FIG. 2 correspond to a split in the integral form of rail 12of FIG. 1 shown by the broken line A. The split may be of other forms.However, description now is directed to the form resulting in themodification shown in FIG. 2, with relevant corresponding features ofFIG. 1 having the reference numerals used in relation to FIG. 2.

The respective form of parts 13 and 15 of rail 12 are shown most clearlyin the exploded perspective view of FIG. 2. Part 13 of FIG. 2 has aninner, upstanding wall 17 which defines a laterally extending,longitudinal rib 18 by which it is engageable with part 15. At the outerside of wall 17, part 13 has a side wall which includes a lower,upwardly and outwardly divergent portion 20 and an upwardly extendingupper portion 21. At its upper edge, side wall portion 21 has a rib 22which extends laterally inwardly in the direction of rib 18, while lowerportion 20 defines a bearing surface 23.

Part 15 of lower rail 12 of FIG. 2 has a solid body 24 which, along itsinner side 25, defines a laterally open groove 26. Outwardly from side25, body 24 defines an upwardly and outwardly inclined top bearingsurface 27 and, at the outer extent of surface 27, part 15 has anupwardly extending side wall 28. Projecting outwardly beyond wall 28,body 24 is provided with a longitudinal series of laterally projectingteeth 29.

Rail 12, where comprising parts 13 and 15, is formed by joining theparts 13 and 15 together. For this, the inner side of wall 17 is urgedagainst side 25 so as to locate rib 18 in groove 26, with rib 18 being aneat fit in groove 26. The parts 13 and 15 can be secured in thisrelationship, such as by bonding with an epoxy resin or welding, or byscrews or rivets inserted laterally through part 15 so as to engage inholes 30 in rib 18 (see FIG. 3). With parts 13 and 15 secured together,bearing surfaces 23 and 27 are mutually inclined at a similar, oppositeangle to a vertical plane through rail 12. Also, rail 12 defines anupwardly open, longitudinal channel 32 of which surfaces 23 and 27define the base, while side wall portion 21 and wall 28 define the sidesof channel 32.

Rail 14 of FIG. 1 is similar to rail 14 of FIG. 3, and has an elongatebody 34 and a side plate 36 which extends upwardly from body 34. Thebottom surface of body 34 defines two mutually inclined longitudinalbearing surfaces 38 and 40 which are at substantially the sameinclination to a vertical plane as surfaces 23 and 27 of rail 12.

Side plate 36 of rail 14 is offset to one side of a central, verticalplane through body 34, such that plate 36 is above bearing surface 40.Over a part of the length of rail 14 which is spaced from each of itsends, the side of body 34 to which plate 36 is offset defines a shortseries of longitudinally spaced, laterally open pockets or recesses 42.Above the first and last of recesses 42, a respective opening 44 isprovided through plate 36. At each side of each opening 44, side plate36 has a vertical rib 46 on its face remote from recesses 42, with eachrib 46 defining a longitudinal groove 48. Also, at the side of body 34further from plate 36, body 34 defines a longitudinal, laterally opengroove 50.

Rail 12, of each form shown in FIGS. 1 to 3, is of substantially uniformcross-section throughout at least a major part of its length, except forthe variation in that section resulting from teeth 29. Similarly, ineach of FIGS. 1 and 3, rail 14 is of substantially constantcross-section throughout a major part of its length, except for thevariation in that section resulting from recesses 42, the openings 44and the ribs 46.

Rail 14, in each arrangement of FIGS. 1 to 3, is mounted on and movablealong rail 12. For this, body 34 is received in channel 32 with itsbearing surfaces 38 and 40 opposed to respective bearing surfaces 23 and27 of rail 12. As shown in FIG. 1, a respective series of bearing rolls52 is provided between opposed bearing surfaces 23 and 38 and betweenbearing surfaces 27 and 40. As also shown in FIG. 1, body 34 is retainedin channel 32 by rib 22 of rail 12 locating in groove 50 of rail 14. Thesame can apply in the case of FIG. 3, although the height of rib 22 andof groove 50 can be such that the respective bearing surfaces are indirect sliding contact.

The locking member 16 is of somewhat C-shape in end elevation. Also. ithas a longitudinal extent which is short relative to the length of therails 12 and 14. The length of the locking member 16 correspondssubstantially to the longitudinal spacing between openings 44 of plate36, and to the longitudinal extent of the series of recesses 42 of body34, of rail 14.

Locking member 16, when viewed in perspective, has the general formshown for locking member 116 of FIGS. 4 to 6. Locking member 16 may beof integral form or, as described later herein with reference to FIG. 6,it may be of segmented form and secured in assembly by any suitablemeans.

Locking member 16 has a somewhat rectangular body 54 which is laterallyadjacent to and extends above and below a region along which rail 14 issupported on rail 12. Locking member 16 also has a respective arm 56projecting from each end of the upper edge 54a of body 54, and arespective leg 58 projecting from each end of the lower edge 54b of body54. Each arm 56 projects upwardly and inwardly from edge 54a, while eachleg 58 extends inwardly, and is slightly inclined downwardly from edge54b.

A short distance below edge 54a, locking member 16 has an array of threeupper teeth 60 which are spaced in the direction of the longitudinalextent of rails 12 and 14. Also, adjacent to edge 54b, locking member 16has a similar array of lower teeth 62.

Locking member 16 is mounted in relation to rails 12 and 14 as shown inFIG. 1. As is evident from FIG. 1, locking member 16 is arranged suchthat its body 54 is adjacent to the side of rail 12 along which teeth 29are disposed and the side of rail 14 at which recesses 42 open. Also,locking member 16 is disposed such that the end of each arm 56 which isremote from body 54 projects from that side of rail 14, through arespective opening 44, to the other side of rail 14. Additionally, eachleg 58 of locking member 16 extends below rail 12 such that its endremote from body 54 is opposed laterally to an abutment surface 64 ofbody 24 of rail 12. The projecting ends of each arm 56 has a pivot pin66 secured in its bore 56a, with the projecting ends of each pin 66located in a respective groove 48 of a rib 46 of plate 36. Thearrangement is such that locking member 16 is pivotably on a common axisof pins 66 between its engagement position, as shown in solid line inFIG. 1, and a retracted position shown in broken outline in FIG. 1. Theteeth 60 and the teeth 62 are spaced in the respective array such that,with locking member 16 in its engagement position, each tooth 60 isreceived in a respective recess 42 of rail 14 and teeth 62 mesh withselected teeth 29 of rail 12, to thereby restrain rail 14 againstmovement along rail 12. Locking member 16 moves to its retractedposition by pivoting in an anti-clockwise direction as viewed in FIG. 1.In the retracted position, teeth 62 are out of engagement with teeth 29,to enable movement of rail 14 along rail 12, with that retractedposition being set, for example, by engagement of each arm 56 with theupper peripheral edge of its opening 44. With locking member 16 in itsretracted position, teeth 60 preferably are only partially withdrawnfrom recesses 42, with co-operation between teeth 60 and recesses 42serving to guide locking member 16 in its pivotal movement. With rail 14moved to a new longitudinal location along rail 12, locking member 16 isallowed to return to its engagement position, with teeth 62 meshing withdifferent ones of the series of teeth 29.

Means (not shown) is provided to move locking member 16 to itsengagement position. For example, a leaf spring may be mounted on plate36 of rail 14, above locking member 16, and act resiliently on one oreach of arms 56. Alternatively, a leaf spring may be mounted on rail 12,and act on the external surface of at least one of legs 58 of lockingmember 10. In a further alternative, a coil spring can be mountedbetween rail 12 and at least one of legs 58. In each case, such springacts as biasing means which biases the locking member to its lockingposition.

Rail 12 is adapted to be secured to the substructure, pan or floor of avehicle, with rail 14 secured to a vehicle seat. The securement of rail12 can be by any suitable arrangement known in the art, such as arespective bracket or the like at each end thereof.

Rail 14 is adapted for securement to the underside of a vehicle seat atlocations along its side plate 36. The securement can be by any suitablemeans, also well known in the art.

Pivotal movement of locking member 16 can be by any suitable means wellknown in the art. Thus, there may be a longitudinal release bar whichextends along one side of mechanism 10, and which is manually rotatablefor pivoting of locking member 16. Such bar may be an extension of onepivot pin 66, or the bar may extend through bores 56a and provide thepivot pin 66 for each arm 56 of locking member 16.

As indicated, the modification of mechanism 10 envisaged by FIG. 2 isthe provision of a two part rather than a unitary rail 12. FIG. 3 showsa similar modification but in other respects is the same as FIG. 1,apart from the square form of rib 22 and the configuration of teeth 29.In mechanism 10 of FIG. 1, and with the modifications of one or each ofFIGS. 2 and 3, locking member 16 when in its engagement position servesa function additional to that of preventing movement of rail 14 alongrail 12. Specifically, locking member 16 restrains rail 14 from liftingaway from rail 12. This further function also is served at one side ofrails 12 and 14 by engagement of rib 22 of rail 12 in groove 50 of rail14, although locking member 16 significantly enhances this engagement atthe other side of rails 12 and 14 at least when locking member 16 is inits engagement position.

As shown in FIG. 1, in which locking member 16 is in its engagementposition, each tooth 60 of locking member 16 is located in a respectiverecess 42 of rail 14 such that a lower surface of the tooth 60 bearsdown on the lower peripheral surface of its recess 42. Also, the uppersurface of each leg 58 of locking member 16 bears upwardly against adownwardly facing abutment portion of surface 64 of rail 12. Thus, rails12 and 14 are held in their required relationship, between and by theaction of teeth 60 and legs 58. Indeed, even with locking member 16 inits retracted position, shown in broken outline in FIG. 1, thisrelationship is substantially retained by virtue of the pivotablemounting of locking member 16 on plate 36 of rail 14 and the closelocation of legs 58 below the lower extent of teeth 29 of rail 12.

The arrangement of the second mechanism of FIGS. 4 to 6 is similar tothose of FIGS. 1 to 3 and will be readily understood. Correspondingcomponents have the same reference numerals plus 100, and description islimited to matters of difference.

There in fact are several differences in the mechanism 110 of FIGS. 4 to6. These principally reside in the form of each of rails 112 and 114 andthe provision of a respective locking member 116 and 116' on each sideof rails 112 and 114. Moreover, as is evident from FIGS. 4 and 5, rail114 is of substantially symmetrical form. Also, as is shown in FIG. 4,rail 112 is an assembly of parts 113 and 115 but, overall, issubstantially symmetrical.

The parts 113 and 115 are inter-related and joined together as describedfor rail 12 of FIG. 2. However, part 115 has a side wall 128 with alaterally, inwardly extending rib 122', similar to wall 121 and rib 122of part 113. Also, part 113 has teeth 129', corresponding to teeth 129of part 115 but projecting in the opposite lateral direction.

The body 134 of rail 114 has a respective laterally open groove 150 and150' along each of its opposite sides. Rail 114 is supported in channel132 of rail 112 in a similar manner to the corresponding rails ofFIG. 1. However, each of grooves 150 and 150' receives a respective oneof ribs 122 and 122' of rail 112, to restrain rail 114 from lifting fromrail 112.

For each of the locking members 116 and 116', the plate 136 of rail 114has a respective set of recesses 142 and 142' and a respect pair ofopenings 144 and 144'. The locking members 116 and 116' are partiallylongitudinally offset, to accommodate location of their arms 156 and156' in respective pairs of openings 144 and 144'. Also, plate 136 ofrail 114 has, adjacent at least one opening 144 and 144' of each pair, arespective pair of ribs 146 and 146' each provided with a groove 148 and148'. As shown most clearly in FIG. 5, recesses 142 and 142' (142' notvisible in FIG. 5) of each set are defined between body 134 and arespective rib 72 and 72' of rail 114.

FIG. 6 shows locking member 116, although locking member 116' isidentical and merely reversed end for end. Locking member 116 is shownas being of integral form, having a solid body 154, 154 ' a pair of arms156, 156' and a pair of legs 158, 158' with a set of upper teeth 160,160' engageable respectively in recesses 142, 142' of rail 114, and aset of lower teeth 162, 162' for meshing with teeth 129, 129' of rail112. The corresponding parts of locking member 116' are correspondinglydesignated where visible.

It is noted that in FIG. 6, reference numeral 156a is a bore, 154a is anedge, and 154b is an edge. Furthermore, in FIG. 4, reference numeral 118is a longitudinal rib, 123 and 127 are bearing surfaces, 126 is agroove, 138 and 140 are bearing surfaces, and 152 are bearing rolls.

Operation of the mechanism 110 of FIGS. 4 to 6 is similar to that of thepreviously described mechanisms. As will be appreciated, each of thelocking members 116 and 116', when in its engagement position as shownin FIG. 4 restrains rail 114 against movement along rail 112. Also, eachof the locking members 116 and 116' needs to be moved to its retractedposition, by opposite pivotal movement, to free rail 114 for suchmovement. The locking members 116 and 116' may be moved to theirengagement positions by suitable means for example, resilient biasingmeans acting between them, or by a respective biasing means for each ofthe locking members 116 and 116'.

The provision of the two locking members 116 and 116' provides for addedsafety, such as in the event of extreme side loadings as can occur whena vehicle suffers a severe side collision. In the event of resultantside forces twisting the vehicle body and acting to displace one oflocking members 116 and 116', the same forces also will act to retainthe other locking member in its engagement position.

Simultaneous movement of each of the locking members 116 and 116' can bearranged in a variety of ways. In one convenient arrangement for this, afirst of the locking members is pivotable under the action of a manuallyoperable release bar coupled with it, with the first locking membercoupled to the second locking member by means of a flexible cable whichpasses from the first, and beyond the second locking member, and returnsto the latter after passing around a pulley mounted on a fixture of thevehicle.

In mechanism 110, rail 114 is restrained from lifting off rail 112 bylocation of ribs 122 and 122' of rail 112 in respective grooves 150 and150' of rail 114. However, in the manner described for mechanism 10 ofFIG. 1, each of the locking members 116 and 116' supplements andenhances this restraint. This applies at least while the locking membersare in their respective engagement positions, but preferably also whenin their respective retracted position.

Also, in mechanism 110, locking member 116 is shown as being of integralform, with the same applying to locking member 116'. However, ifrequired, these locking members could be made in a segmented form, withsegments shown by broken lines B, and by securing the segments inassembly by any suitable means.

It will be appreciated that, with each mechanism 10 and 110 shown in thedrawings, a laterally spaced, parallel pair of the mecnanisms is used toprovide mounting for a seat to enable adjustment of the seat in the foreand aft directions. Where each mechanism of the pair has a singlelocking member, a single actuator may provide for pivoting of bothlocking members in unison to their retracted positions. Alternatively,the actuator may act directly on only one of the locking members, withthe other pivoting in unison with and in response to pivoting of the onelocking member by means of a link, coupling or cable between the lockingmembers. Where each mechanism has two locking members, the actuatorusually will act directly on one locking member of each pair, ordirectly on one locking member of one of the mechanisms, with the otherlocking members pivoting in response to pivoting of the or each lockingmember on which the actuator acts. Of course, it is possible for onemechanism to have two locking members, and the other to have only onelocking member.

In each mechanism 10 (and 110) illustrated in the drawings, the rails 12(112) and 14 (114), and locking members 16 (116, 116') and their partswhere made separately, preferably are cast from a light weight metal bypressure diecasting, most preferably of a magnesium or aluminium alloy,or a respective such alloy for different components. However, they canbe diecast from zinc alloy, while casting other than diecasting and useof other metals is possible. Also, one or more of the components can beinjection molded from an engineering plastics material, such as nylon orPTFE, or cast or moulded from a metal matrix composite material or madeby a suitable powder metallurgy process. Particularly where diecast, andof a magnesium and/or aluminum alloy, the mechanisms 10 (and 110') havea high integral load bearing capacity, as well as a relatively highstrength to weight ratio.

The locking member 16 (or locking members 116 and 116') lock with eachof rails 12 and 14 (or 112 and 114) and this reduces loading at the siteof their pivot pin or pins 66 (or 166 and 166'). This double lockingarrangement thus adds to safety in minimising risk of failure in theevent of a front or rear end collision. Also, the extension of thelocking members 16 (or 116 and 116') around the rails 12 and 14 (or 112and 114) safeguard against their displacement in the event of a sideimpact.

In each of the mechanisms 10 (or 110) illustrated in the drawings, thelocking member 16 (or 116 and 116') engages with teeth 29 (or 129 and129') or recesses between these teeth of a longitudinal series thereofalong the fixed rail 12 (or 112). The series of teeth may extend alongthe full length of the rail. However, the series need only extend alonga rail to an extent consistent with the full range of movement of rail14 (or 114) along rail 12 (or 112), over that part of the length of rail12 (or 112) traversed by the locking member or locking members in suchrange.

In each of the mechanisms illustrated in the drawings, the or eachlocking member is pivotable on the movable rail, and locks with thefixed rail. However, it is to be appreciated that a converse arrangementis possible, with the or each locking member pivotable on the fixed rail12 (or 112) and able to lock with the movable rail 14 (or 114).

In each of the mechanisms shown in the drawings, the fixed rail and themovable rail usually will have a length which is a major part of thefore to aft dimension of a vehicle seat with which they are to be used.That dimension frequently is about 400 mm. The rails may be of a similarlength, while a usual range of fore and aft adjustment required for avehicle seat is about 250 mm. The locking member or locking members canbe provided at any suitable location along the rails, but it usually isconvenient for access to an actuator to have the locking member orlocking members at the forward half of the rails.

The dimensions of the or each locking member can vary substantially.However, as is evident from the drawings, its height may be similar toits length longitudinally of the rails. Also, that length is a minorpart of the length of the rails, and may for example be from about 40 to80 mm. The longitudinal extent of the array of teeth, projections,recesses or the like, such as teeth 29 of FIGS. 1 to 3, and of teeth 29(129 and 129') in FIGS. 4 to 6, with which the locking member or eachlocking member engages to prevent movement of the movable rail along thefixed rail, need not extend along the full longitudinal extent of thefixed rail. The same applies when the locking member or each lockingmember is pivotably mounted on the fixed rail and the teeth projections,recesses or the like are defined by the movable rail. In each case, itis sufficient if the extent of the array of teeth, projections, recessesor the like along the relevant rail is about equal to the sum of thelength of the locking member longitudinally of the rails plus the extentto which the movable rail is to be adjustable along the fixed rail.

As will be appreciated from the preceding description, and theillustrated embodiments, the mechanism of the invention has numerousadvantages. The track components are amenable to manufacture in aninter-locking form. The locking member component itself enhancesinter-locking of the rails and, at least to this extent, can proceedsubstantially beyond merely providing a component which, as with theconventional locking member, only locks the tracks in a chosenlongitudinal relationship. The track components can be of a unique formwhich provides for self-alignment and, as a consequence, both increasedresistance to side impact forces and wider manufacturing tolerances.

The mechanism also is amenable to integration of additional componentsthat normally are assembled on to tracks, such as track mounting feet,mounting points for height adjustment, a recliner facility and seat beltanchor points. Moreover, while components of the mechanism can beproduced from steel fabrications or the like, they also are suitable forpressure diecasting from alloys of magnesium, aluminium or zinc, ormolding from engineering plastics material. Thus, the mechanism can beof relatively light weight, but have an enhanced strength to weightratio. Also, where cast or molded, the components can require little orno subsequent machining or other finishing.

The interlocking arrangement possible for the tracks and the lockingmember (or locking members) can significantly enhance safety, inparticular can provide improved crash performance. Moreover, this can beachieved with a saving in weight and with a reduced number of distinctcomponent forms.

The invention is able to be modified in a number of respects, withoutdeparting from the spirit of the present disclosure. Thus, for example,the relationship between the locking member or locking members and thefixed track can be modified to enhance both retention of thatrelationship and overall safety. In each of the illustrated embodiments,there is, for example, a close spacing between the bottom of the fixedtrack and the locking member(s). However, given that the or each lockingmember is pivotable about an axis that may be, and preferably is,parallel to the tracks, the bottom of the fixed track and the adjacentpart of the locking member can have a respective arcuate surface whichhas a center of curvature at that axis, with the respective arcuatesurfaces in sliding contact.

Finally, it is to be understood that various alterations, modificationsand/or additions may be introduced into the constructions andarrangements of parts previously described without departing from thespirit or ambit of the invention.

What is claimed is:
 1. A seat mounting mechanism for mounting a seat foradjustable fore and aft movement, the mechanism comprising:an elongatefixed rail securable to a substructure, pan or floor; an elongatemovable rail engageable with the fixed rail and securable to a seat; atleast one locking member mounted on one of the fixed and movable railsand pivotable between an engagement position for locking the movablerail relative to the fixed rail and a retracted position for freeing themovable rail for adjustment along the fixed rail, wherein, the lockingmember is mounted for movement about a pivot axis extendingsubstantially parallel to the fixed and movable rails; the at least onelocking member has engagement means selectively engageable withengagement means disposed along the other of the fixed and movablerails; and the at least one locking member includes inter-fitting meanslocated intermediate the pivot axis and the engagement means of the atleast one locking member, said inter-fitting means is inter-fit withinter-fitting means formed on said one of the fixed and movable rails atleast when the locking member is in the engagement position and saidinter-fitting means of the locking member is at least Partiallywithdrawn from said inter-fit with said inter-fitting means formed onsaid one of the fixed and movable rails as said at least one lockingmember is pivoted from said engagement position to said retractedposition.
 2. The mechanism of claim 1, wherein the movable rail is anupper rail supported on the fixed rail; and wherein the locking memberextends from the pivot axis to one side of the rails and across a regionwhere the movable rail is supported on the fixed rail, to a region wherethe engagement means of the locking member is engageable with theengagement means on the other of the fixed and movable rails.
 3. Themechanism of claim 1, wherein the engagement means of the locking membercomprises a plurality of lateral projections and the engagement means ofthe second rails comprises a series of laterally open recesses definedalong the second rail.
 4. The mechanism of claim 1, wherein theengagement means of the locking member comprises a plurality oflaterally open recesses and the engagement means of the other of thefixed and movable rails comprises a series of lateral projectionsdefined therealong.
 5. The mechanism of claim 1, wherein the lockingmember is mounted on the movable rail and the engagement means of thelocking member comprises lateral projections; the engagement means ofthe other of the rails comprises a series of laterally open recessesdefined along the fixed rail; and said lateral projections are receivedin selected ones of the laterally open recesses when the locking memberis in the engagement position.
 6. The mechanism of claim 1, wherein thelocking member is mounted on the movable rail and the engagement meansof the locking member comprises a series of laterally open recesses; theengagement means of the other of the rails comprises a series of lateralprojections formed along the fixed rail; and said laterally openrecesses receive selected ones of said lateral projections when thelocking member is in the engagement position.
 7. The mechanism of claim1, wherein said inter-fitting means of the locking member has at leastone abutment surface which, at least when the locking member is in itsengagement position, abuts against at least one abutment surface of saidone of the fixed and movable rails, whereby the rails are restrainedfrom separating from engagement with each other by combined action ofabutment of said respective at least one abutment surfaces andengagement between the respective engagement means.
 8. The mechanism ofclaim 1, wherein the respective interfitting means each comprises aplurality of lateral projections with the projections of the lockingmember meshing with the projections of said one of the fixed and movablerails.
 9. The mechanism of claim 1, wherein the interfitting means ofthe locking member comprises a plurality of teeth and the interfittingmeans of said one of the fixed and movable rails comprises a pluralityof laterally open recesses for receiving respective teeth of saidplurality of teeth.
 10. The mechanism of claim 1, wherein the lockingmember has at least two arms projecting from a main body portion, saidmain body portion is located on a first side of the rails, said at leasttwo arms extend through said one of the fixed and movable rails, saidlocking member is pivotally mounted on said one of the fixed and movablerails at a second side of said one of the first and movable rails,opposite the first side.
 11. The mechanism of claim 10, wherein thelocking member as viewed in a longitudinal direction of the rails is ofC-shaped configuration, the locking member having a portion remote fromsaid arms extending across an edge of the other of the fixed and movablerails and terminating adjacent to the first side of the other of thefixed and movable rails when in the engagement position.
 12. Themechanism of claim 1, wherein the locking member is of integral orunitary construction.
 13. The mechanism of claim 1, wherein the lockingmember is formed of a plurality of parts secured together at adjacentsurfaces extending laterally with respect to the rails.
 14. Themechanism of claim 1, wherein the locking member is cast from a group oflight metal alloys consisting of aluminum, magnesium and zinc alloy. 15.The mechanism of claim 1, wherein the locking member is molded fromplastic.
 16. The mechanism of claim 1, wherein the movable rail is ofintegral or unitary form and is molded from plastic.
 17. The mechanismof claim 1, wherein the fixed rail defines an upwardly facing,longitudinal surface on which the movable rail is supported, and themovable rail has a downwardly facing bearing surface for being supportedon the fixed rail for movement therealong.
 18. The mechanism of claim17, wherein the rails are in direct, sliding contact at the respectivebearing surfaces.
 19. The mechanism of claim 17, wherein bearing meansare provided between the respective surfaces.
 20. The mechanism of claim17, wherein the bearing surface of the fixed rail has the form of aV-section trough, and the bearing surface of the movable rail is ofcomplementary form to the bearing surface of the fixed rail.
 21. Themechanism of claim 1, wherein the fixed rail has at least oneupstanding, longitudinal side wall laterally adjacent to a lower portionof the movable rail, and wherein a laterally extending rib on the sidewall is located in a longitudinal slot defined by said lower portion toprevent the movable rail from lifting from the fixed rail.
 22. Themechanism of claim 1, wherein the movable rail is of integral or unitaryform and is cast from a group of light alloys consisting of aluminum,magnesium and zinc alloy.
 23. The mechanism of claim 1, wherein themovable rail has a lower, longitudinal body portion for being mounted onthe fixed rail and an upwardly extending longitudinal plate and saidplate is securable to a seat.
 24. The mechanism of claim 1, wherein thefixed rail is cast from a group of light alloys consisting of aluminum,magnesium and zinc alloy.
 25. The mechanism of claim 1, wherein thefixed rail is of integral or unitary form.
 26. The mechanism of claim24, wherein the fixed rail comprises at least two longitudinal partssecurable together as an assembly.
 27. The mechanism of claim 1, whereinthe fixed rail is molded from plastic.
 28. A seat mounting mechanism formounting a seat for adjustable fore and aft movement, the mechanismcomprising:an elongate fixed rail securable to a substructure, pan orfloor; an elongate movable rail engageable with the fixed rail andsecurable to a seat; two locking members each mounted on one of thefixed and movable rails and pivotable between an engagement position forlocking the movable rail relative to the fixed rail and a retractedposition for freeing the movable rail for adjustment along the fixedrail, wherein each locking member is mounted for movement about arespective pivot axis extending substantially parallel to the fixed andmovable rails; each locking member has engagement means selectivelyengageable with respective engagement means disposed along the other ofthe fixed and movable rails; and each locking member includesinter-fitting means located intermediate the respective pivot axis andthe respective engagement means of the locking member, saidinter-fitting means of each locking member is inter-fit with respectiveinter-fitting means formed on said one of the fixed and movable rails atleast when the locking member is in the engagement position and saidinterfitting means of the locking member is at least partially withdrawnfrom said inter-fit with said respective inter-fitting means formed onsaid one of the fixed and movable rails as said one locking member ispivoted from said engagement position to said retracted position;wherein said locking members are in an opposed relationship with therails extending therebetween and are oppositely pivotable between saidengagement and retracted positions.
 29. A seat mounting mechanism formounting a seat for adjustable fore and aft movement, the mechanismcomprising:an elongate fixed rail securable to a substructure, pan orfloor; an elongate movable rail engageable with the fixed rail andsecurable to a seat; at least one locking member mounted on the movablerail and pivotable between an engagement position for locking themovable rail relative to the fixed rail and a retracted position forfreeing the movable rail for adjustment along the fixed rail, whereinthe locking member is mounted for movement about a pivot axis extendingsubstantially parallel to the fixed and movable rails; the at least onelocking member has engagement means selectively engageable withengagement means disposed along the fixed rail; and said at least onelocking member includes inter-fitting means located intermediate thepivot axis and the engagement means of the at least one locking member,said inter-fitting means is inter-fit with inter-fitting means formed onthe movable rail at least when the locking member is in the engagementposition and said inter-fitting means of the locking member is at leastpartially withdrawn from said inter-fit with said inter-fitting meansformed on said one of the movable rails as said at least one lockingmember is pivoted from said engagement position to said retractedposition.
 30. The mechanism of claim 29, wherein the locking member hasat least two arms projecting from a main body portion, said main bodyportion is located on a first side of the rails, said at least two armsextend through the movable rail, said locking member is pivotablymounted on the movable rail at a second side of the movable rail,opposite the first side.
 31. The mechanism of claim 30, wherein thelocking member as viewed in a longitudinal direction of the rails is ofC-shaped configuration, the locking member having a portion remote fromsaid arms extending across an edge of said movable rail and terminatingadjacent to the first side of the fixed rail when in the engagementposition.